The mixture of organoclays and polyamides, commonly called “nanonylons”, is highly desired because the organoclays can contribute barrier properties to polyamides for food packaging and other situations where the contained product within packaging must not leach, escape, or decay. Polyamides have been useful since the mid-20th Century. Organoclays, nanoclays intercalated with organic ions, such as quaternary ammonium, have become useful commercially in the last decade.
Presently, nanonylons can be made using two conventional processes: (1) melt mixing of the organoclay into the previously polymerized nylon, in which the clay is added to a nylon melt by mechanical action; and (2) in-situ polymerization of the nylon in the presence of the organoclay, in which a batch of monomer such as caprolactam is brought to polymerization in a vessel also containing organoclay.
An example of melt mixing is found in U.S. Pat. No. 6,605,655 (Kato et al.). An example of in-situ polymerization is found in U.S. Pat. No. 4,739,007 (Okada et al.).